1. Field of the Invention
The present invention relates to a jump wire structure having jump wires arranged on a printed circuit board.
2. Related Art
As is well known, a printed circuit board has electronic parts and/or devices such as CPU, ROM, condensers, resistors, diodes or transistors mounted on its upper or front side. The printed circuit board has a circuit pattern printed on its lower or rear side.
Such electronic parts and/or devices can be mounted on the printed circuit board by inserting their opposite terminal leads into through holes made in the printed circuit board, and by bending these leads on the lower or rear side of the board for soldering their terminal ends to the printed circuit pattern. Usually, many parts and devices are arranged in a limited space of the board. When the number of parts and devices increases beyond a permissible mounting density, it is necessary that printed circuit boards large enough to meet the permissible mounting density be used.
JP 6-334290(A) has proposed a three-dimensional wiring structure in which two jump wires cross each other, or a jump wire and a circuit component cross each other on a printed circuit board. This crossing arrangement significantly improves a mounting density with which circuit components are mounted on the printed circuit board. Jump wires make it possible to shorten a length of component-to-component connection. Advantageously, this shortening contributes to suppression of radiation of electromagnetic waves and appearance of noise signals in printed circuits.
Specifically, two jump wires cross each other on a front or upper side of a printed circuit board. Each jump wire has its opposite ends bent and passing through holes, which are provided in the printed circuit board. These holes extend from the front to a rear side of the board to correspond to terminal ends of selected conductors in an electric circuit, which is printed on a rear surface of the board. The opposite ends of each jump wire passing through the board and appearing on the rear side are soldered to the terminal ends of selected conductors in this printed circuit.
Assuming that such jump wires 6 are parallel-arranged as shown in FIG. 5(a), and that an external force is applied to any one or ones of these parallel jump wires 6 so as to be bent or inclined toward an adjacent jump wire, they often come to touch one another, thereby causing short circuits to appear in printed circuit 1.
Assuming that two parallel jump wires 6a and 6b lie across a circuit component as shown in FIG. 5(b), and that an external force is applied to these jump wires, they are often inclined toward each other so as to be in contact with one another. Then, short circuits will be caused in printed circuit 1.
In view of the above, one object of the present invention is to provide a jump wire structure for a printed circuit board, guaranteed to be free of causing short-circuits no matter whether jump wires are parallel-arranged or laid across each other on the printed circuit board.